Conventionally, there has been known a damping valve that controls a damping force of a shock absorber interposed between a vehicle body and an axle shaft of a vehicle to be variable. For example, as illustrated in FIG. 9, a damping valve described in JP2014-173714A includes a port (not illustrated) through which fluid flows during extension and contraction of a shock absorber, a main valve (not illustrated), which opens and closes an outlet of the port, a pilot passage 180, which guides pressure on the upstream side of the port as back-pressure of the main valve, a fail passage 190, which branches from the middle of the pilot passage 180, a pilot valve element 600, which is disposed in the middle of the pilot passage 180 and includes a seating portion 601 to open and close the upstream side with respect to a branching part 191 of the fail passage 190 in the pilot passage 180 and an annular projection 602 to open and close the downstream side with respect to the branching part 191 in the pilot passage 180, a coil spring 610, which biases the pilot valve element 600 in a direction of opening the upstream side with respect to the branching part 191 and closing the downstream side in the pilot passage 180, a solenoid S, which provides thrust to the pilot valve element 600 in a direction against biasing force from the coil spring 610, and a fail valve 192 disposed at the fail passage 190.
The damping valve with the configuration adjusts an energization amount to the solenoid S to adjust the thrust provided to the pilot valve element 600, thus controlling the back-pressure of the main valve. Additionally, changing a valve opening pressure of the main valve ensures controlling a damping force of the shock absorber variable. Additionally, during a fail during which a current supply to the solenoid S is cut off, the pilot valve element 600 receives the biasing force from the coil spring 610 and closes the downstream side with respect to the branching part 191 in the pilot passage 180. However, an increase in pressure of fluid inside the pilot passage 180 opens the fail valve 192; therefore, the fluid flows through the fail passage 190. Accordingly, by changing the valve opening pressure of the fail valve 192, the valve opening pressure of the main valve during the fail is set, thus any damping force characteristics generated in the shock absorber during the fail can be set.